Prophylactic use of levosimendan in pediatric patients undergoing cardiac surgery: the jury is still out

Excerpt

The study by Wang et al. on levosimendan used in prophylaxis of low cardiac output syndrome (LCOS) post-pediatric cardiac surgery is the first study comparing levosimendan versus placebo. The authors did not show an impact on mortality or on the occurrence of LCOS [1]. However, it is very interesting to see that in the multivariate regression analysis, levosimendan had an impact on the onset of LCOS (OR 0.38 and p = 0.037). We are not surprised by the absence of an impact on mortality given the small number of patients. In a Cochrane review, Hummel et al. estimated that the number of pediatric patients required to prove the superiority of levosimendan for outcome mortality was 652 [2]. We wonder how levosimendan could prevent LCOS. LCOS in a heart with good preoperative function is linked to inadequate myocardial protection during aortic clamping, poorly performed cardioplegia, myocardial reperfusion lesions, ventriculotomy, preoperative arrhythmias, activation of inflammatory cascades and complement, and alterations of pulmonary and systemic vascular resistances [3, 4]. Because of its intrinsic mode of action as a calcium sensitizer, we could expect levosimendan to improve cardiac function after surgery but probably not to prevent intraoperative events. The study of Wang et al. showed the safety of using levosimendan in a population with a preoperative cardiac index of 3.3 ml/min/m² and low-risk adjustment in congenital heart surgery (RACHS) [5]. This may lead to another question: are those patients sick enough to show a benefit from levosimendan? The study therefore opens the door to others comparing levosimendan to placebo in more severe pediatric patients with higher RACHS, preoperative decompensation, and/or low cardiac output with a cardiac index < 2.2 L min/m². …